Diaphragm mounting



April 21, 1953 J. H. NELLIS 2,635,640

DIAPHRAGM MOUNTING Filed Feb. 12, 1948 5 Sheets-Sheet l m a Q N Q Q 5 Qw FIGJ INVENTOR.

J. H. NELLIS DIAPHRAGM MOUNTING April 21, 1953 5 Sheets- Sheet 2 FiledFeb. 12, 1948 INVENTOR.

I i i l A ril 21, 1953 J. H. NELLIS 2,635,640

DIAPHRAGM MOUNTING Filed Feb. 12, 1948 5 Sheets-Sheet 3 IN VEN TOR.

April 21, 1953 J. H. NELLIS 2,635,640

DIAPHRAGM MOUNTING Filed Feb. 12, 1948 5 Sheets-Sheet 4 INSULATON FIG. 5/6-7 A57 93 74 L53 2&8

Patented Apr. 21, 1953 DIAPHRAGM MOUNTING James H. Nellis, Dayton, Ohio,assignor to General Motors Corporation, Dayton, Ohio, a corporation ofDelaware Application February 12, 1948, Serial No. 7,882

2 Claims.

This invention relates to controls particularly intended for use with anelectric range, but which have many features applicable to othercontrols.

It is an object of my invention to provide a simple, quick and easymeans for accurately calibrating and recalibrating the control devicewithout the use of customary obstinate locking devices.

To attain these objects I have provided a wafer type diaphragm meanswith an offset welded radial flange. This diaphragm means operates theprimary lever of a snap-action mechanism which is connected by a thinmetal member to one end of a toggle lever which is linked to one leg ofeach of two L-shaped contact members. A toggle spring is connected tothe other end of the toggle lever and maintains a tension upon thetension member and provides the force for snapaction.

The interior of the wafer type diaphragm member is connected by a tubeto an ordinary thermostat bulb which is charged with an expansibleliquid. This tube prevents rotation of the diaphragm means. Thediaphragm means is provided with a rotatable connection with anexternally threaded member. An arm having a friction connection with theexternally threaded member normally prevents its rotation. Theexternally threaded member is surrounded by and in threaded engagement,with an internally threaded member rotatably mounted in the switch case.A knob is provided on the internally threaded member. The normaltemperature adjustment is accomplished by rotating the knob and theinternally threaded member relative to the internally threaded member tomove the diaphragm means inwardly or outwardlyaccording to thetemperature selected. If it is desired to change the calibration, theinternally threaded member is prevented from rotating and the plug isforcibly rotated relative to the internally threaded member to changethe position of the diaphragm means.

The internally threaded member in the broil position operates a camwhich lifts the second leg of each of the L-shaped contacts todisconnect both ends of the lower heating unit. A U-shaped member, alsooperated by this cam, is provided with an arm which operates thepreheat-bake switch to lift it into the preheat position. An adjunct tothis U-shaped member is used to provide an automatic preheat-bakecontrol in which the preheat-bake change is made before the temperatureis attained to which the thermostat is set. To this end the L l-shapedmember which operates the preheat-bake switch has a projection with ashoulder thereon which in the preheat or broil position rests againstthe end of the primary lever of the snap-action switch mechanism. Thisholds the preheat-bake arm in the preheat position when the knob ismoved away from the broil position to a selected temperature. Prior tothe reaching of this selected tempera ture, the expansion of thediaphragm will move the primary lever to disengage the shoulder from themain lever to allow the U-shaped member and its preheat-bake arm to movethe preheatbake contacts to the baking position.

Further objects and advantages of the present invention will be apparentfrom the following description, reference bein had to the accompanyingdrawings, wherein a preferred form of the present invention is clearlyshown.

In the drawings:

Fig. l is a sectional view taken along the lines ll of Figs. 2 to 4, 6and 7;

Fig. 2 is a top view with the cover removed of my improved control,together with a Wiring diagram of an oven;

Fig. 3 is a sectional view taken along the lines 33 of Figs. 1, 6 and 7;

Fig. 4 is a bottom view of the frame and snapaction mechanism;

Fig. 5 is an irregular fragmentary sectional view taken in part alongthe lines 55 of Fig. 2 to show the preheat-bake switch mechanism;

Fig. 6 is a sectional view taken along the lines 6.6 of Figs. 1 to 5;

Fig. 7 is a sectional view taken along the lines 1-l of Figs. 1 to 5;

Fig. 3 is a top view of the diaphragm means; and

Fig. 9 is a wiring diagram ior one type of oven circuit.

Referring now to the drawings and more particularly to Figs. 1, 3, 7, 8and 9, there is shown a wafer type diaphragm means 20 preferably made ofa thin upper nickel iron chrome alloy disk 22, and a thin lower nickeliron chrome alloy disk 24. The central portion of the upper disk ispreferably welded or otherwise bonded to a follower 25. The centralportion of the lower disk 24 is provided with a small aperture whichregisters with a tiny central aperture in the hub 28 to which it iswelded or otherwise bonded. A radial transverse passage in this hub 28connects the interior of the diaphragm means 20 with the capillary tube30 which is provided with an offset and then extends through a rubbergrommet 32 which fills an aperture in that portion of the lower case 34.The capillary tube 30 connects to a thermostat bulb located in heatexchange relation with the oven compartment. Preferably the end of thetube 30 is flared and projection-welded to the hub 28 as shown inFig. 1. To facilitate this the side to which the tube 30 is connected isprovided with a fiat surface.

The portion of each of the diaphragms 22 and 2 3 immediately surroundingthe follower portion of the oven portion are corrugated in concentriccircles to increase their flexibility. Beyond this concentriccorrugated. portion, there is provided a wide offset flange which isoffset from the corrugated portion an amount at least four'times theheight of the corrugations. The offset flange 33 has a width about equalto two corrugations and in the conventional 1 wafer diaphragm thisamounts to a width of about .150". To bond the oifset flanges of thediaphragms 22 and 24 together, preferably a seam weld 3% in width ismade entirely around the oifset flange 36 to bond the flanges together.Preferably this weld is made about in the middle of the flange 36 andspaced from the outside edge of the flange about The offset 38 protectsthe weld 40 from excessive stress and strain and provides addedflexibility which prevents cracking of the diaphragms under life tests.Because the flange 33 is radial and flat the diaphragms are radiallybonded together with a tight joint.

The follower 26 upon the upper diaphragm 22 engages a projection 62 uponthe primary lever 34. The primary lever 44 is provided with a pin itwhich is welded in a transverse notch provided in the lever 44. This pin46 has reduced end portions which are received in a pair of notches 48provided in the lower edge of the frame 53. The primary lever 44 isprovided with a longitudinal stiffening rib. At the end of the long armof the lever 44 there is provided a post 52 to which is riveted one endof a thin metal tension member 54. This member 541 may have alongitudinal slot therein to improve its flexibiiity. The opposite endof this tension member is riveted to the contact end of the toggle lever56. The opposite end of this toggle lever 53 is provided with a pair ofoifset ears 58 which ride in a pair of notches 6B in an adjacent portionof the frame 58. Also connected to these cars are a pair of tensiontoggle spring 62, the other ends of which are connected to atransversely curved thin metal anchoring member 64 mounted in a pair ofslots 66 in the opposite sides of the frame 56.

The contact end of the toggle lever 56 is turned up and has riveted toit a U-shaped member 68 of insulating material. This U-shaped memberextends through suitable apertures into the contact case Iii made of asuitable electrical insulating material such as porcelain. This U-shaped member 68 extends through transverse slots in a pair of L-shapedcontact members I2 and It and is connected there by cotterpins above andbelow the members '32 and I4 as shown in plug 8 3 is threaded into theinternally threaded sleeve 83 having external grooves 9'8 and a curvedleaf spring 92 for holding a suitable knob 3 in dicated in dot and dashlines. The sleeve 3% is provided with an annular bead 93 on the insideof the casing 34 and is locked in place axially by a snap ring 98 whichfits into the circumferential groove in the sleeve 88 and bears againsta shoulder on the casing 34. This allows the sleeve 88 to be rotatedrelative to the case 34 but me vents it from being moved axially,although its assembly is made easy.

At one side of the bead 96 there is provided a cam I2I which is fixed tothe sleeve 38 by riveting over the adjacent end. This cam I2I isprovided with notches I23 and I25 which cooperate with the V-shapedportion of the leaf spring 42'! riveted to the case 341 to provide astop to limit the rotation of the knob at the off and broil positions atthe two ends of the temperature range. A hump is provided between eachof these notches and the remaining portion of the cam I2I so as toprovide a definite feel or sensible indication when the spring I21passes into the ofi or broil notches. The springs i2? also serve toprovide suificient friction to hold the knob 94 in any position to whichit may be set.

To prevent normal rotation of the plug 84 an arm I29 is rotatablymounted thereon between a C-shaped washer I3! held within a groove inthe plug 35, and a shoulder upon the plug 34. This plug 84 is normallyprevented from rotating by a curved spring I33 which forces the arm I25against the C-shaped washer ISI with suificient force to prevent normalrotation of the plug 8 3 relative to the arm I29. The arm I29 isprovided with an offset and extends radially outwardly. The end of thearm I29 is forked to receive one of the four spacing pins i35 which holdthe frame 50 and the case 34 in proper relationship. The engagement ofthe forked end of the arm with the one spacing pin I35 allows the plugto move axially but the arm normally prevents its rotation unless achange in setting is desired.

When a change in setting is desired, the knob 94 is removed and thesleeve 88 is held. A screw driver is then inserted in the slot in theexternal end of the plug 84 and the plug 88 is turned with sufficientforce to overcome the friction provided by the spring I33 to whatevernew calibrating point is desired, to provide a different relationshipbetween the sleeve 88 and the location of the diaphragm means 29. Inmaking such a calibration adjustment it should be noted that all that isnecessary is to remove the knob as. No lock nuts or screws are requiredto be loosened.

Surrounding the bead 96 and held in place by the cam I2I is the hub I31of a cam I39. In the broil position, this cam I 39 is coupled throughthe use of a projection I4I fixed to and extending fromthe cam IZI. Thecam I39 is normally held in retracted position by a tension coil springI43 which extends between an ear on the cam I39 and an arm extendingfrom the leaf spring I21 which is fastened to the case 34. When the knob94 is turned to the broil position, as shown in Fig. 3 the projectionI4I engages the arm of the cam I39 to cause it as shown in Fig. 6 toengage the nose I45 of the cross member I4! which connects to the lowerends of the pins I49. These pins I49, when raised by the engagement ofthe cam I39 with the nose I45, lift the transverse legs I5I and I53 ofthe L- shaped contact members I4 and I2. These transverse legs IfSI and.I53 carry contact buttons adapted to make contact with the lower ovenheating unit connecting terminals I55 and I51. These terminals I55 andI51 connect directly with the opposite ends of the lower heating unitI59. When the pins I49 are raised by the cam I39, the contact buttons onthe legs I5I and IE3 of the L-shaped contact members 14 and 12 arelifted from the terminals of the lower heating unit I59 so that therewill be no danger of a shock by touching the lower oven heating unit I59during the broil period.

The raising of the cross member I41 also raises a U-shaped member I6Iwhich normally rests upon the cross member I41. This U-shaped member IEIis pivoted by the pin I63 to the frame 59. The yoke I65 of the U-shapedmember I6I carries an adjustable member I61 provided with an apertureI99 which normally receives the tongue I1I at the extreme end of theprimary lever 44. The upper end of the aperture I99 normally limits theupward or counterclockwise movement of the primary lever 44. However,when the control knob 94 is turned to the broil position, the shoulderI13 at the upper end of the aperture I69 is moved away from the tongueH! to allow the tongue I1I to rise above the upper end of the apertureI69 directly opposite the shoulder I13. When the knob 94, after beingfirst set to the broil position, is then returned to the temperatureselected for baking, the U-shaped member IBI is prevented from followingthe cross member I41 downwardly by the engagement of the end of thetongue I1I with the shoulder I13.

One leg I15 of the U-shaped member ItI projects through a slot in a pushbar I11 which extends upwardly through an aperture in the contact case10 into engagement with the blade of the preheat-bake switch I19anchored at the one end to the preheat-bake terminal I8I. The free endof the blade I19 carries contact buttons above and below. A coil spring230 is wrapped around the push bar I 11 between the leg I15 and theflange of the frame 59 to normally hold the push bar 11 and blade I19 intheir lower positions. In the upper position of the blade I19 thecontact buttons engage a stationary contact member I83 which extends toa point over the junction of the two legs of the L-shaped contact member12. A contact button upon each of the members 12 and I83 at this pointprovides a point of electrical connection between these members and alsoserves as a means for pivoting either of the legs of the L-shaped member12.

The terminal IBI is connected by a conductor I85 to an intermediatepoint of the two connected upper heating unit sections I81 and I89. Theother end of the section IE9 is connected by the conductor I9! to theneutral supply conductor 6 and through this circuit all of the heatingelements are grounded when the contacts 12 and 14 are open. The otherend of the other upper heating unit section I81 is connected directly tothe terminal I93 which has a contact button over the contact button atthe junction of the two legs of the L-shaped contact member 14. Thejunction of the two legs of each of the L- shaped contact members areheld in contact with the members I83 and I93 by a springbacked memberI95 of an electrical insulating resin beneath which is a small coilspring I91. As is better shown in Fig. 6 this member I95 has twoprojections extending through two apertures in the bottom of the contactcase 10, which 6 extend into engagement with the extreme end portion ofthe junction of the two legs of the L-shaped contact members 12 and 14.This keeps the L-shaped contact members 12 and 14 electrically connectedto the members I83 and I93 at all times.

A lower contact member I99 is provided in the switch which extends to aterminal 220 for using the switch with a different oven circuitarrangement. This terminal 220 may be connected to a tap upon lower ovenheating unit when a c'ucuit is used like that shown in the Weimer Patent2,218,778, issued Oct. 22, 1940. In this Patent 2,218,778 the tap isdesignated by reference character 24. The contact case is closed by athin cover 222 of electrical insulating material which is normally heldin place by a screw 224.

In normal operation, the thermostat is cold when the control is turnedon. If quick preheating is not desired the knob is turned directly tothe legend indicating the bake temperature desired. The setting of theknob 94 adjusts the position of the hub 48 and the diaphragm means 20relative to the primary lever 44 to move the toggle 56 to open theswitch contact 14 and 12 at the temperature selected. Under suchcircumstances the cam I39 as well as the cross member I41 and theU-shaped member I5I remain motionless and inactive in their lowerpositions. The opening temperature of the switch contacts may beadjusted so that they conform exactly to the setting of the knob 94 byholding the knob stationary at the setting desired and holding thesleeve 88 in the knob at the setting desired and turning the threadedplug 94 until the contacts 12 and 14 are open at the exact temperaturedesired. Since the threaded plug 84 can be turned to any desired pointthe adjustment is infinite within the range of operation of the switch.

For broiling the knob 94 is turned directly to the broil position andthe projection I4I engases the arm of the cam I39 and forces it beneaththe nose I45 of the cross member I41, as shown in Fig. 6, to raise thepins I49 to lift the transverse legs I5! and I53 of the L-shaped contactmembers 14 and 12 to disconnect them from the terminals I55 and I51 ofthe lower oven heating unit I59 located within the oven compartment I69.This connects the supply conductor 89 through the terminal 19, contactmember 12 and the member I83 with the preheat-bake blade I19 whichthrough the terminal l8! and the conductor I85 connects to the upperheating unit composed of sections I91 and I89. This connects unit I89across the supply conductors 8D and I 9I The other upper" heating unitsection I81 through the terminal I93, the contact 14 and the terminal18, is connected to the other live supply conductor 82. If the voltageacross the supply conductors 80 and 82 is 230 volts this voltage isimpressed on the section I81 while volts is impressed upon the sectionI89. This provides an adequate amount of heat for broiling purposes.

For quick preheating the knob is first turned to the broil position andthen immediately returned to the desired baking temperature. When thisis done the hub 28 and the diaphragm means 29 are moved towards the knob94 a sufficient distance so that the tongue I1I at the extreme end ofthe primary lever 44 rises above the upper end of the aperture I69 inthe member I61. At the same time the cam I39 will lift the pins I49 asexplained for the broil position, but as soon as the knob is turned awayfrom the "broil position they will be dropped and returned to the bakeposition. In the broil position the U-shaped member Ifii is also liftedby the cross member I41, but when the knob 94 is returned to theselected baking temperature the U-shaped member I6I does not follow thereturn of the cross member I41 to its original lower position but isheld in its upper or preheat position by the engagement of the end ofthe tongue I1I with the shoulder I13 of the member I61. The position ofthe shoulder I13 may be adjusted by loosening the screw 225 (see Fig. 5)and turning the screw 228 until the shoulder I13 is positioned at theproper point to be held by the tongue I1I when the knob 9-4 is turned tothe broil position and to be released at a temperature and position ofthe tongue just prior to the tripping temperature and position. Thisholds the U-shaped member I'EI as well as the push bar I11 and thepreheat-bake blade I19 in the preheat circuit position against the forceof the coil spring 239 which is Wrapped around the push bar I11.

In the preheat position, the upper heating unit is energized as in thebroil position, but since the pins I49 have been dropped the contacts 12and 14 are again in contact with the terminals I51 and I55, so that thelower oven heating unit I59 is energized at the full line voltage. Asthe oven compartment I69 is heated to a temperature approaching that forwhich the knob 94 is set, the wafer diaphragm 29 will be expandedsufficiently to cause the tongue Hi to move from the shoulder I13 intoaperture I59. This will permit the spring 239 to push the U-shaped leverdownwardly so that the blade I19 will be enabled to make contact withthe contact member I99. When the temperature is reached for which theknob 94 is set, the post 52 will, through the tension member 54, pullthe contact end of the toggle lever 56 across its dead center positionto open the contacts 12 and 14. Sufficient cooling of the ovencompartment I59 will cool the thermostat bulb suificiently to contractthe wafer diaphragm means 29 to move the toggle member 56 back acrossthe dead center position to close the contacts 12 and 14. When this isdone the lower oven heat unit I 59 is connected directly across the twolive supply conductors 80 and 82 as before. However, the preheat-bakeblade I19 remains in its lower position against the contact I99 therebykeeping the conductor I85 disconnected from the live supply conductor86. The current from the upper heating unit is then supplied from thelive supply conductor 82 through the terminal 18, the contact 14, theterminal I93 to the upper oven heating unit section I81 through whichthe current flows to the other'upper heating unit section I89 which isconnected to the neutral conductor I9I. This arrangement then connectsthe two upper heating units I81 and I89 in series across the conductors82 and I9I impressing a voltage of nominally volts to provide a smallamount of top heat for good baking conditions.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, as may come Within the scope of the claims.

What is claimed is as follows:

1. A control including an actuating means in the form of two thin metaldisks each having a radial flange, said flanges being bonded togetherthroughout an entire circle, a concentrically located hub fastened'toone of said disks, a threaded member provided with a rotatableconnection with said hub, frictional means for normally preventing therotation of said threaded member, a rotatably mounted member in threadedengagement with said threaded member for changing the location of saiddisks, and means for preventing axial movement of the rotatably mountedmember.

2. A control including a diaphragm means, a concentrically located hubfastened to said diaphragm means, a threaded member provided with arotatable connection with said hub, frictional means for normallypreventing the rotation of said threaded member, a rotatably mountedmember in threaded engagement with said threaded member for changing thelocation of said diaphragm means and means for preventing axial movementof the rotatably mounted member.

JAMES H. NELLIS.

References Cited in the file of this patent UNITED STATES PA'IENTSNumber Name Date 800,945 Scott Oct. 3, 1905 1,561,065 Eggleston Nov. 10,1925 1,836,634 Urfer Dec. 15, 1931 1,966,537 Binckley July 17, 19841,978,362 Fonseca Oct. 23, 1934 2,123,829 Grayson July 12, 19382,237,530 Olley Apr. 8, 1941 2,289,020 Jones July 7, 1942 2,295,427Puster Sept. 8, 1942 2,338,271 Ulanet Jan. 4, 1944 2,347,185 FentressApr. 25, 1944 2,385,434 Weber Sept. 25, 1945 2,402,354 Waddell June 18,1946

